In American Demon: Eliot Ness and the Hunt for America’s Jack the Ripper (Minotaur, Sept.), Stashower explores the legendary lawman’s career after the arrest of Al Capone.

What was your family connection to Ness?

In researching this book, I’m scrolling through a microfilm copy of Eliot Ness’s scrapbooks. As you might expect, there are a lot of articles featuring Capone and other gangsters, and the era’s shining lights—FDR, John D. Rockefeller, J. Edgar Hoover. I did not expect to see my grandfather, Fred, in the scrapbooks. Ness and my grandfather crossed paths at least yearly at a political roast staged by local businessmen. My grandfather was a cast member, and Ness was a frequent target when Ness was the public safety director in Cleveland.

Why call Ness’s achievements in Cleveland a “miracle”?

Ness was put in charge of the police and fire departments, and a whole lot more, in one of America’s biggest cities. He had been brought in by a reform-minded mayor looking to clean up the town and make it once again a place where people could do business. This mayor brought in Ness to weed out corruption and racketeering, and graft. A lot of people assumed that the job was impossible, but Ness really did a good job of reforming the police department and helping to clean up the city.

But Ness didn’t catch the Torso killer, who murdered at least a dozen people.

The point that often gets overlooked is that Ness wasn’t in the business of catching murderers. He was at the top of the pyramid. The chief of police reported to Ness. Ness was also in charge of the fire department, and people didn’t expect him to put out house fires or rescue cats stranded in trees. He was the man in charge of allocating the resources.

Is it possible to state conclusively whether the murders were the work of one person or more than one person?

There are a lot of variables in the case, which makes it very difficult. People group the victims differently. With Jack the Ripper, the victims were female prostitutes. Here, it’s men and women, Blacks and whites, straights and gays. It’s all over the map. So it’s very hard to detect a pattern in this. There were all kinds of real headaches for the investigators, including that some of the victims couldn’t be identified at all—and then questions were raised about the handling of the evidence. At a remove of 90 years, it’s very hard to go back and say, well, this is definitely true about the murders. It’s a very slippery series of crimes.